Hartwigsen Gesa, Siebner Hartwig R
Language and Aphasia Laboratory, Department of Neurology, University of Leipzig, Leipzig, Germany.
Front Neurol Neurosci. 2013;32:101-11. doi: 10.1159/000346431. Epub 2013 Jul 8.
The neural mechanisms that support aphasia recovery are not yet fully understood. It has been argued that the functional reorganization of language networks after left-hemisphere stroke may engage perilesional left brain areas as well as homologous right-hemisphere regions. In this chapter, we summarize how noninvasive brain stimulation can be used to elucidate mechanisms of plasticity in language networks and enhance language recovery after stroke. We first outline some basic principles of transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS). We then present evidence from studies in healthy volunteers for a causal role of the right hemisphere in different language functions. Finally, we review recent studies that used TMS or tDCS to promote language recovery after stroke. Most of these studies applied noninvasive brain stimulation over contralateral right-hemisphere areas to suppress maladaptive plasticity. However, some studies also suggest that right-hemisphere regions may beneficially contribute to recovery in some patients. More recently, some investigators have targeted perilesional brain regions to promote neurorehabilitation. In sum, these studies indicate that language recovery after stroke may integrate left- as well as right-hemisphere brain regions to a different degree over the time course of recovery. Although the results of these preliminary studies provide some evidence that noninvasive brain stimulation may promote aphasia recovery, the reported effect sizes are not striking. Future studies on larger patient collectives are needed to explore whether noninvasive brain stimulation can enhance language functions at a level that is clinically relevant.
支持失语症恢复的神经机制尚未完全明确。有人认为，左半球中风后语言网络的功能重组可能涉及病灶周围的左脑区域以及右侧半球的同源区域。在本章中，我们总结了如何利用非侵入性脑刺激来阐明语言网络可塑性的机制，并促进中风后的语言恢复。我们首先概述经颅磁刺激（TMS）和经颅直流电刺激（tDCS）的一些基本原理。然后，我们展示来自健康志愿者研究的证据，证明右半球在不同语言功能中起因果作用。最后，我们回顾最近使用TMS或tDCS促进中风后语言恢复的研究。这些研究大多对右侧半球对侧区域进行非侵入性脑刺激，以抑制适应不良的可塑性。然而，一些研究也表明，右侧半球区域可能对某些患者的恢复有有益贡献。最近，一些研究人员将病灶周围脑区作为靶点来促进神经康复。总之，这些研究表明，中风后的语言恢复在恢复过程中可能在不同程度上整合了左、右半球脑区。虽然这些初步研究的结果提供了一些证据表明非侵入性脑刺激可能促进失语症恢复，但报告的效应大小并不显著。需要对更大的患者群体进行未来研究，以探索非侵入性脑刺激是否能在临床相关水平上增强语言功能。
